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A081534
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Numbers n such that sum 1+2 ... +n divides LCM (1,2,3....n), or in other words LCM(n) is a multiple of the n-th triangular number.
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0
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1, 3, 5, 7, 9, 11, 13, 14, 15, 17, 19, 20, 21, 23, 25, 27, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 43, 44, 45, 47, 49, 50, 51, 53, 54, 55, 56, 57, 59, 61, 62, 63, 64, 65, 67, 68, 69, 71, 73, 74, 75, 76, 77, 79, 81, 83, 84, 85, 86, 87, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 101
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| n(n+1)/2 divides n! if n+1 is not a prime.
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FORMULA
| Union of odd numbers and even numbers k such that k+1 is neither prime nor prime power. - Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 30 2003
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CROSSREFS
| Cf. A006134.
Sequence in context: A082655 A050828 A194391 * A097218 A196546 A007617
Adjacent sequences: A081531 A081532 A081533 * A081535 A081536 A081537
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 28 2003
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EXTENSIONS
| More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 07 2003
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